Twenty-first federal electoral district of Mexico City

The twenty-first federal electoral district of Mexico City (Distrito electoral federal 21 de la Ciudad de México; previously "of the Federal District") is one of the 300 electoral districts into which Mexico is divided for elections to the federal Chamber of Deputies and one of the 22 currently operational districts in Mexico City.

It elects one deputy to the lower house of Congress for each three-year legislative period, by means of the first past the post system. Votes cast in this district also count towards the calculation of proportional representation ("plurinominal") deputies elected from the fourth region.

District territory
Under the 2023 districting plan, which will be used for the 2024, 2027 and 2030 federal elections, the 21st district covers the borough (alcaldía) of Milpa Alta and the bulk of Xochimilco excluding the north-western portion assigned to the 5th district.